Abstract
A 14-year-old boy presented with a 1.5 cm erythematous nodule on the left shoulder. The lesion was asymptomatic but had been present and growing over the last three months. An excisional biopsy was performed and showed a relatively well-circumscribed tumor situated within the dermis and superficial subcutis. In the central portion of the lesion, there were solid nests and sheets of epithelioid cells with vesicular nuclei and abundant pale eosinophilic cytoplasm. Significant pleomorphism was not seen. The cells were surrounded by fibrotic stroma with a patchy infiltrate of lymphocytes, histiocytes, and plasma cells. Towards the periphery of the lesion, well-formed vascular spaces with surrounding inflammation including many eosinophils were noted. The epithelioid cells were positive for ERG and negative for CAMTA and FosB1 by immunohistochemistry. A diagnosis of cellular epithelioid hemangioma was rendered. Epithelioid hemangiomas (EH) are relatively rare benign vascular tumors that were first described in the skin and superficial soft tissue but can occur at various anatomic sites including bone, deeper soft tissue, and viscera. Cellular EH has solid areas that are composed of epithelioid cells with prominent nucleoli and eosinophilic cytoplasm. This variant of EH may pose a diagnostic challenge as the differential diagnosis includes malignant epithelioid vascular neoplasms such as epithelioid hemangioendothelioma and epithelioid angiosarcoma. Key histologic features, including peripheral circumscription, presence of well-formed vascular spaces at least at the periphery of the tumor, and lack of significant cytologic atypia, can aid in distinguishing cellular EH from these malignant vascular tumors.
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